我想将Bitmap
缩放为与运行时相关的宽度和高度,其中保持纵横比,Bitmap
填充整个宽度并垂直居中图像,裁剪多余的或用0像素填充间隙。
我目前正在通过创建所有0个像素的Bitmap
并在其上方绘制图像Bitmap
,缩放到指定的指定宽度并保持纵横比来自行重绘位图,然而,它最终会丢失/搞砸像素数据。
以下是我的表现:
Bitmap background = Bitmap.createBitmap((int)width, (int)height, Config.ARGB_8888);
float originalWidth = originalImage.getWidth(), originalHeight = originalImage.getHeight();
Canvas canvas = new Canvas(background);
float scale = width/originalWidth;
float xTranslation = 0.0f, yTranslation = (height - originalHeight * scale)/2.0f;
Matrix transformation = new Matrix();
transformation.postTranslate(xTranslation, yTranslation);
transformation.preScale(scale, scale);
canvas.drawBitmap(originalImage, transformation, null);
return background;
是否有一个库或一些更好的代码可以做得更好?我希望图像看起来尽可能清晰,但我知道我的功能不会提供很好的结果。
我知道通过使用整数缩放而不是浮点缩放可以使图像保持正常,但我需要宽度为100%填充。
另外,我知道ImageView
的{{1}}功能,它也使用整数缩放,所以当它不应该时,它会切断图像的宽度。
答案 0 :(得分:80)
这将尊重maxWidth和maxHeight,这意味着生成的位图的尺寸永远不会大于:
private static Bitmap resize(Bitmap image, int maxWidth, int maxHeight) {
if (maxHeight > 0 && maxWidth > 0) {
int width = image.getWidth();
int height = image.getHeight();
float ratioBitmap = (float) width / (float) height;
float ratioMax = (float) maxWidth / (float) maxHeight;
int finalWidth = maxWidth;
int finalHeight = maxHeight;
if (ratioMax > ratioBitmap) {
finalWidth = (int) ((float)maxHeight * ratioBitmap);
} else {
finalHeight = (int) ((float)maxWidth / ratioBitmap);
}
image = Bitmap.createScaledBitmap(image, finalWidth, finalHeight, true);
return image;
} else {
return image;
}
}
答案 1 :(得分:64)
这个怎么样:
Bitmap background = Bitmap.createBitmap((int)width, (int)height, Config.ARGB_8888);
float originalWidth = originalImage.getWidth();
float originalHeight = originalImage.getHeight();
Canvas canvas = new Canvas(background);
float scale = width / originalWidth;
float xTranslation = 0.0f;
float yTranslation = (height - originalHeight * scale) / 2.0f;
Matrix transformation = new Matrix();
transformation.postTranslate(xTranslation, yTranslation);
transformation.preScale(scale, scale);
Paint paint = new Paint();
paint.setFilterBitmap(true);
canvas.drawBitmap(originalImage, transformation, paint);
return background;
我添加了paint
来过滤缩放后的位图。
答案 2 :(得分:22)
这里我有一个经过测试的解决方案,我用位图文件创建了一个缩放的Bitmap:
int scaleSize =1024;
public Bitmap resizeImageForImageView(Bitmap bitmap) {
Bitmap resizedBitmap = null;
int originalWidth = bitmap.getWidth();
int originalHeight = bitmap.getHeight();
int newWidth = -1;
int newHeight = -1;
float multFactor = -1.0F;
if(originalHeight > originalWidth) {
newHeight = scaleSize ;
multFactor = (float) originalWidth/(float) originalHeight;
newWidth = (int) (newHeight*multFactor);
} else if(originalWidth > originalHeight) {
newWidth = scaleSize ;
multFactor = (float) originalHeight/ (float)originalWidth;
newHeight = (int) (newWidth*multFactor);
} else if(originalHeight == originalWidth) {
newHeight = scaleSize ;
newWidth = scaleSize ;
}
resizedBitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, false);
return resizedBitmap;
}
请注意,我需要缩放的位图,其最大尺寸为4096x4096像素,但在调整大小时需要保持纵横比。如果您需要宽度或高度的其他值,只需替换值#34; 4096"。
这只是Coen答案的补充,但他的代码中的问题是他计算比率的线。除以两个整数得到一个整数,如果结果是< 1它将四舍五入为0.所以这会将"除以零"异常。
答案 3 :(得分:17)
这是我的Utils类的一个方法,它完成了这项工作:
public static Bitmap scaleBitmapAndKeepRation(Bitmap targetBmp,int reqHeightInPixels,int reqWidthInPixels)
{
Matrix matrix = new Matrix();
matrix .setRectToRect(new RectF(0, 0, targetBmp.getWidth(), targetBmp.getHeight()), new RectF(0, 0, reqWidthInPixels, reqHeightInPixels), Matrix.ScaleToFit.CENTER);
Bitmap scaledBitmap = Bitmap.createBitmap(targetBmp, 0, 0, targetBmp.getWidth(), targetBmp.getHeight(), matrix, true);
return scaledBitmap;
}
答案 4 :(得分:6)
更简单的解决方案:请注意我们将宽度设置为500像素
public void scaleImageKeepAspectRatio()
{
int imageWidth = scaledGalleryBitmap.getWidth();
int imageHeight = scaledGalleryBitmap.getHeight();
int newHeight = (imageHeight * 500)/imageWidth;
scaledGalleryBitmap = Bitmap.createScaledBitmap(scaledGalleryBitmap, 500, newHeight, false);
}
答案 5 :(得分:5)
也可以通过自己计算比率来完成,就像这样。
private Bitmap scaleBitmap(Bitmap bm) {
int width = bm.getWidth();
int height = bm.getHeight();
Log.v("Pictures", "Width and height are " + width + "--" + height);
if (width > height) {
// landscape
int ratio = width / maxWidth;
width = maxWidth;
height = height / ratio;
} else if (height > width) {
// portrait
int ratio = height / maxHeight;
height = maxHeight;
width = width / ratio;
} else {
// square
height = maxHeight;
width = maxWidth;
}
Log.v("Pictures", "after scaling Width and height are " + width + "--" + height);
bm = Bitmap.createScaledBitmap(bm, width, height, true);
return bm;
}
答案 6 :(得分:4)
上述答案都没有为我工作,我只是创建了一个方法,将所有尺寸设置为所需尺寸,并将空白区域绘制为黑色。这是我的方法:
/**
* Scale the image preserving the ratio
* @param imageToScale Image to be scaled
* @param destinationWidth Destination width after scaling
* @param destinationHeight Destination height after scaling
* @return New scaled bitmap preserving the ratio
*/
public static Bitmap scalePreserveRatio(Bitmap imageToScale, int destinationWidth,
int destinationHeight) {
if (destinationHeight > 0 && destinationWidth > 0 && imageToScale != null) {
int width = imageToScale.getWidth();
int height = imageToScale.getHeight();
//Calculate the max changing amount and decide which dimension to use
float widthRatio = (float) destinationWidth / (float) width;
float heightRatio = (float) destinationHeight / (float) height;
//Use the ratio that will fit the image into the desired sizes
int finalWidth = (int)Math.floor(width * widthRatio);
int finalHeight = (int)Math.floor(height * widthRatio);
if (finalWidth > destinationWidth || finalHeight > destinationHeight) {
finalWidth = (int)Math.floor(width * heightRatio);
finalHeight = (int)Math.floor(height * heightRatio);
}
//Scale given bitmap to fit into the desired area
imageToScale = Bitmap.createScaledBitmap(imageToScale, finalWidth, finalHeight, true);
//Created a bitmap with desired sizes
Bitmap scaledImage = Bitmap.createBitmap(destinationWidth, destinationHeight, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(scaledImage);
//Draw background color
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.FILL);
canvas.drawRect(0, 0, canvas.getWidth(), canvas.getHeight(), paint);
//Calculate the ratios and decide which part will have empty areas (width or height)
float ratioBitmap = (float)finalWidth / (float)finalHeight;
float destinationRatio = (float) destinationWidth / (float) destinationHeight;
float left = ratioBitmap >= destinationRatio ? 0 : (float)(destinationWidth - finalWidth) / 2;
float top = ratioBitmap < destinationRatio ? 0: (float)(destinationHeight - finalHeight) / 2;
canvas.drawBitmap(imageToScale, left, top, null);
return scaledImage;
} else {
return imageToScale;
}
}
例如;
假设您的图像为100 x 100但所需尺寸为300x50,则此方法会将图像转换为50 x 50并将其绘制为尺寸为300 x 50的新图像(并且空文件将为是黑色的。
另一个例子:假设您的图像为600 x 1000,所需的尺寸再次为300 x 50,那么您的图像将被转换为30 x 50并绘制成新创建的图像,尺寸为300 x 50
我认为这是必须的,Rs。
答案 7 :(得分:3)
在Gowrav的回答中添加了RESIZE_CROP。
enum RequestSizeOptions {
RESIZE_FIT,
RESIZE_INSIDE,
RESIZE_EXACT,
RESIZE_CENTRE_CROP
}
static Bitmap resizeBitmap(Bitmap bitmap, int reqWidth, int reqHeight, RequestSizeOptions options) {
try {
if (reqWidth > 0 && reqHeight > 0 && (options == RequestSizeOptions.RESIZE_FIT ||
options == RequestSizeOptions.RESIZE_INSIDE ||
options == RequestSizeOptions.RESIZE_EXACT || options == RequestSizeOptions.RESIZE_CENTRE_CROP)) {
Bitmap resized = null;
if (options == RequestSizeOptions.RESIZE_EXACT) {
resized = Bitmap.createScaledBitmap(bitmap, reqWidth, reqHeight, false);
} else {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float scale = Math.max(width / (float) reqWidth, height / (float) reqHeight);
if (scale > 1 || options == RequestSizeOptions.RESIZE_FIT) {
resized = Bitmap.createScaledBitmap(bitmap, (int) (width / scale), (int) (height / scale), false);
}
if (scale > 1 || options == RequestSizeOptions.RESIZE_CENTRE_CROP) {
int smaller_side = (height-width)>0?width:height;
int half_smaller_side = smaller_side/2;
Rect initialRect = new Rect(0,0,width,height);
Rect finalRect = new Rect(initialRect.centerX()-half_smaller_side,initialRect.centerY()-half_smaller_side,
initialRect.centerX()+half_smaller_side,initialRect.centerY()+half_smaller_side);
bitmap = Bitmap.createBitmap(bitmap, finalRect.left, finalRect.top, finalRect.width(), finalRect.height(), null, true);
//keep in mind we have square as request for cropping, otherwise - it is useless
resized = Bitmap.createScaledBitmap(bitmap, reqWidth, reqHeight, false);
}
}
if (resized != null) {
if (resized != bitmap) {
bitmap.recycle();
}
return resized;
}
}
} catch (Exception e) {
Log.w("AIC", "Failed to resize cropped image, return bitmap before resize", e);
}
return bitmap;
}
答案 8 :(得分:2)
public static Bitmap scaleBitmap(Bitmap bitmap, int wantedWidth, int wantedHeight) {
float originalWidth = bitmap.getWidth();
float originalHeight = bitmap.getHeight();
Bitmap output = Bitmap.createBitmap(wantedWidth, wantedHeight, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
Matrix m = new Matrix();
float scalex = wantedWidth/originalWidth;
float scaley = wantedHeight/originalHeight;
float xTranslation = 0.0f, yTranslation = (wantedHeight - originalHeight * scaley)/2.0f;
m.postTranslate(xTranslation, yTranslation);
m.preScale(scalex, scaley);
// m.setScale((float) wantedWidth / bitmap.getWidth(), (float) wantedHeight / bitmap.getHeight());
Paint paint = new Paint();
paint.setFilterBitmap(true);
canvas.drawBitmap(bitmap, m, paint);
return output;
}
答案 9 :(得分:2)
This is an awesome library from ArthurHub可以通过编程和交互方式处理图像裁剪。
但如果您更喜欢像我这样的非膨胀版本..,此处显示的内部功能相当复杂,可以使用少量标准选项执行图像缩放
/**
* Resize the given bitmap to the given width/height by the given option.<br>
*/
enum RequestSizeOptions {
RESIZE_FIT,
RESIZE_INSIDE,
RESIZE_EXACT
}
static Bitmap resizeBitmap(Bitmap bitmap, int reqWidth, int reqHeight, RequestSizeOptions options) {
try {
if (reqWidth > 0 && reqHeight > 0 && (options == RequestSizeOptions.RESIZE_FIT ||
options == RequestSizeOptions.RESIZE_INSIDE ||
options == RequestSizeOptions.RESIZE_EXACT)) {
Bitmap resized = null;
if (options == RequestSizeOptions.RESIZE_EXACT) {
resized = Bitmap.createScaledBitmap(bitmap, reqWidth, reqHeight, false);
} else {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float scale = Math.max(width / (float) reqWidth, height / (float) reqHeight);
if (scale > 1 || options == RequestSizeOptions.RESIZE_FIT) {
resized = Bitmap.createScaledBitmap(bitmap, (int) (width / scale), (int) (height / scale), false);
}
}
if (resized != null) {
if (resized != bitmap) {
bitmap.recycle();
}
return resized;
}
}
} catch (Exception e) {
Log.w("AIC", "Failed to resize cropped image, return bitmap before resize", e);
}
return bitmap;
}
答案 10 :(得分:1)
我的解决方案是这样,它保持纵横比,并且只需要一个尺寸,例如,如果你有一个1920 * 1080和一个1080 * 1920的图像,你想要将它调整为1280,第一个将是1280 * 720第二个是720 * 1280
public static Bitmap resizeBitmap(final Bitmap temp, final int size) {
if (size > 0) {
int width = temp.getWidth();
int height = temp.getHeight();
float ratioBitmap = (float) width / (float) height;
int finalWidth = size;
int finalHeight = size;
if (ratioBitmap < 1) {
finalWidth = (int) ((float) size * ratioBitmap);
} else {
finalHeight = (int) ((float) size / ratioBitmap);
}
return Bitmap.createScaledBitmap(temp, finalWidth, finalHeight, true);
} else {
return temp;
}
}
答案 11 :(得分:0)
重新缩放图像涉及简单的数学运算,请考虑以下代码片段,然后继续进行操作: 1.假设您有720x1280的Imaan图像,并且要适合420宽度,请获取给定数学所需的缩小百分比,
originalWidth = 720;
wP = 720/100;
/* wP = 7.20 is a percentage value */
wP
。您将获得宽度减小的百分比。 difference = originalWidth - 420;
dP = difference/wP;
这里dP
将为41.66,这意味着您将减小大小41.66%。因此,您必须将高度降低41.66(dP
)才能保持该图像的比例或比例。
计算以下高度,
hP = originalHeight / 100;
//here height percentage will be 1280/100 = 12.80
height = originalHeight - ( hp * dP);
// here 1280 - (12.80 * 41.66) = 746.75
这是您的合适比例,您可以在420x747中调整图像/位图的大小。它将返回经过调整大小的图像,而不会丢失比例/比例。
示例
public static Bitmap scaleToFit(Bitmap image, int width, int height, bool isWidthReference) {
if (isWidthReference) {
int originalWidth = image.getWidth();
float wP = width / 100;
float dP = ( originalWidth - width) / wP;
int originalHeight = image.getHeight();
float hP = originalHeight / 100;
int height = originalHeight - (hP * dP);
image = Bitmap.createScaledBitmap(image, width, height, true);
} else {
int originalHeight = image.getHeight();
float hP = height / 100;
float dP = ( originalHeight - height) / hP;
int originalWidth = image.getWidth();
float wP = originalWidth / 100;
int width = originalWidth - (wP * dP);
image = Bitmap.createScaledBitmap(image, width, height, true);
}
return image;
}
这里您只是参考height或width参数缩放图像以适合所需的条件。
答案 12 :(得分:0)
基于joaomgcd回答的Kotlin扩展功能版本
private fun Bitmap.resize(maxWidth: Int, maxHeight: Int): Bitmap {
return if (maxHeight > 0 && maxWidth > 0) {
val width = this.width
val height = this.height
val ratioBitmap = width.toFloat() / height.toFloat()
val ratioMax = maxWidth.toFloat() / maxHeight.toFloat()
var finalWidth = maxWidth
var finalHeight = maxHeight
if (ratioMax > ratioBitmap) {
finalWidth = (maxHeight.toFloat() * ratioBitmap).toInt()
} else {
finalHeight = (maxWidth.toFloat() / ratioBitmap).toInt()
}
Bitmap.createScaledBitmap(this, finalWidth, finalHeight, true)
} else this
}